Meanwhile, John attempts to court Claire, the maid of honor, but is interrupted by her hotheaded boyfriend, Sack Lodge (Bradley Cooper), who is unfaithful and disrespectful behind her back. When Gloria invites Jeremy and John to an extended weekend party at their family compound, Jeremy tries to refuse due to him being extremely uncomfortable with Gloria. John overrules Jeremy to accept as it would be great to get to know the family. Jeremy reluctantly accepts, although he is suspicious that John only wanted to go just to get closer to Claire.

John and Jeremy become acquainted with the Clearys at their home: the Secretary's wife (Jane Seymour) sexually harasses John; Gloria's brother Todd (Keir O'Donnell) tries to seduce Jeremy during the night; Gloria continues to lavish unwanted sexual attention on Jeremy; and Sack repeatedly injures Jeremy during a game of touch football. During dinner, as a means to get even with Sack for injuring Jeremy along with more time to connect with Claire, John spikes Sack's wine with eye-drops to make him sick and he spends the rest of his night throwing up in the toilet.

John and Claire continue to bond the next day on a sailing trip. The suspicious Sack calls his friend, Trapster, to privately investigate John and Jeremy. He then takes Jeremy hunting, where he is shot in the buttocks. While he recovers, John and Claire go on a bike ride to a secluded beach. Claire finally admits she is unsure how she feels about Sack and ends up kissing John passionately. Meanwhile, Gloria tends to Jeremy's wounds and reveals to him that she is not as innocent or inexperienced as she initially let on. Jeremy realizes that he himself has been played and that he may be in love with Gloria. When Sack falsely claims that he and Claire are engaged, John isn't fooled by this attempt knowing how unhappy she is with him.

Ready to confess everything to Claire about his feelings for her and convince her not to marry Sack, John is interrupted by Jeremy being chased out of the house. Sack reveals John and Jeremy's identities to the family. Betrayed, Claire turns away from John and the Secretary tells them to leave. Gloria tells Jeremy she loves him regardless of his fraudulence.

Over the following months, Jeremy manages to keep his relationship with Gloria a secret. Meanwhile, John attempts to reach Claire but she refuses to see him. He comes up with a plan to see her by disguising himself as a waiter at her and Sack's engagement party. Concerned about John's behavior, Jeremy tries to talk some sense into him by reminding him that his last attempts to speak to her has failed and that he needs to accept the fact that it's over. He also warns John against attempting to crash Claire and Sack's engagement party because of the security of Secretary Cleary’s Secret Service protection. Jeremy mentions that their only chance of avoiding jail time is to keep a low profile and stay away. John ignores the warning and goes forward with his crash plans. Sack catches him and beats him up. John visits Jeremy at his house to confront him for his absence and catches him having sex with Gloria. Betrayed, John walks out of the house and Jeremy follows trying to explain himself, while Gloria leaves to go to the engagement party. Outside, John demanded why he didn't appear to stop Sack and learns that Jeremy had continued his secret relationship with Gloria. John spirals into depression, crashing weddings alone and becoming nihilistic and suicidal. While planning her wedding, Claire's doubts about Sack begin to grow. Jeremy proposes to Gloria and tries to ask John to be his best man, but a depressed John refuses.

John visits Jeremy's former wedding crashing mentor, Chazz Reinhold (an uncredited Will Ferrell), who convinces him to crash a funeral. While there, he reconsiders his belief in love and marriage after witnessing a grieving widow. He rushes to Jeremy's wedding and joins the wedding mid-ceremony to Jeremy's delight. Claire is upset by his appearance, prompting John to profess his love to her and his regret for his past behavior in front of the congregation. Claire finally tells Sack that she cannot marry him. After Secretary Cleary refuses to defend him, Sack angrily demands Claire to get back on the altar. John makes a wisecrack about it and Sack tries to attack him, only for Jeremy to intervene and knock him out.

After the wedding, the two couples drive away from the ceremony together, discussing crashing another wedding together.

Isla Fisher as Gloria Cleary, youngest daughter of William Cleary; an emotionally unstable nymphomaniac who is obsessed with Jeremy.

Jane Seymour as Kathleen "Kitty Kat" Cleary, the "social alcoholic" wife of Secretary Cleary and daughter-in-law of "Grandma" Mary Cleary; she appears to try and hit on younger men, including John and an ex-boyfriend of Claire (this last one revealed by Todd).

Ellen Albertini Dow as "Grandma" Mary Cleary, William's mother, Kathleen's mother-in-law, and the siblings' grandmother who lives in the compound; she is kind but obscene.

Ron Canada as Randolph, the Clearys' Jamaican butler; he seems completely aware of Gloria's obsessive behaviors and does not approve of Sack's hotheadedness.

Jenny Alden as Christina Cleary, the eldest daughter of William Cleary.

Will Ferrell (uncredited) as Chazz Reinhold, the sage who passed on the wedding crashing rules to his protege Jeremy in 1993. When John actually meets him, Chazz is revealed to be a lazy man-child who still lives with his mother.

Arizona Senator and 2008 Republican presidential nominee John McCain and Democratic strategist and CNN contributor James Carville both have a brief cameo appearance in the film towards the beginning, where both are seen congratulating the secretary and his wife on their daughter's wedding.

Dobkin has said that the script originally set the film around Cape Cod, but a need to film in spring made this impractical.[7] He suggested moving the shoot to Washington, his home town, feeling that his knowledge of the area would make choosing locations easier, and that using the city as the setting for a comedy would be an unexpected choice.[8]

Wedding Crashers received generally positive reviews. On Rotten Tomatoes, the film has a rating of 76%, based on 185 reviews, with an average rating of 6.7/10. The site's critical consensus reads, "Wedding Crashers is both raunchy and sweet, and features top-notch comic performances from Vince Vaughn and Owen Wilson."[9] On Metacritic the film has a score of 64 out of 100, based on 39 critics, indicating "generally favorable reviews".[10]

Carina Chocano of the Los Angeles Times wrote a favorable review and said "underneath the diarrhea gags, the long lens at close range of Vaughn's pants and the handcuffs, it's really just a love story about a couple of buddies who live happily ever after. And it couldn't have happened to a nicer, more charming couple".[11]
Manohla Dargis of the New York Times said "It's crude, yes, but also funny; too bad these lost boys can't stay lost. Like clockwork, the film soon mutates from a guy-oriented sex comedy into a wish-fulfillment chick flick".[12]

Roger Ebert of the Chicago Sun-Times gave the film two stars out of four; although he wrote that "there are individual moments that are very funny" he added that the director, David Dobkin, "has too much else on his mind".[13] British Movie magazine Empire awarded it three out of five stars and were complimentary to Vaughn and Wilson, saying "Sharing an easy chemistry and free of the usual joker/straight-guy dynamic, Wilson and Vaughn quip, riff and banter to hilarious effect. And both get their fair share of money moments, the latter’s muggings are particularly hysterical in a raunchy dinner-party sequence. The laidback stars are funny and sweet, but they’re let down by a patchy script which squanders some potentially priceless set-ups."[14]

The film was released in North America on July 15, 2005, and became an immediate hit, grossing $33,900,720 in its first weekend,[15] hitting #2 in the box office, behind Charlie and the Chocolate Factory. Fairly well received by critics, the film eventually grossed over $209,255,921 domestically, narrowly outgrossing Charlie. Considering its modest budget ($40 million) and competition with heavily advertised blockbusters during the summer season, the studio did not expect the movie's astounding level of success. It grossed $75,920,820 overseas, totaling $285,176,741 worldwide.[16]

On April 24, 2006, Wedding Crashers topped the nominations for the year's MTV Movie Awards with five including Best Movie. It won Best Movie, On-Screen Team (Vaughn and Wilson), and Breakthrough Performance (Isla Fisher). The financial success of the film has been credited along with The 40-Year-Old Virgin for reviving the popularity of adult-aimed R-rated comedies.[4]

Bradley Cooper was mentioned in the August 2006 issue of GQ as one of "The Top Twelve Movie Dicks". [17]

The DVD was released in the United States on January 3, 2006, and a Blu-ray was released on December 30, 2008. It is available in an unrated version ("Uncorked Edition") and in an R-rated version (the Blu-ray has both versions on one disc). It features eight new minutes integrated into the film and DVD-ROM bonuses. Also included are two audio commentaries (one by the stars, one by the director), four deleted scenes, two featurettes, a "Rules of Wedding Crashing" text gallery, trailers, BudweiserWedding Crashers commercials, a track listing for the official soundtrack on 20th Century Fox Records, a music video by The Sights, and a jump-to-a-song sample feature.[21]

In a 2014 post on the website Quora, Wedding Crashers director David Dobkin said that he, Vaughn and Wilson once came up with an idea for a sequel in which John and Jeremy find themselves competing with a superior wedding crasher, played by Daniel Craig; but that this idea never went beyond the discussion phase.[23]

The 2013 film The Internship, which also starred Vaughn and Wilson, was sometimes described by critics as an unofficial sequel to Wedding Crashers.[24]

In November 2016, Fisher was a guest on The Today Show and while talking about Nocturnal Animals, she revealed from her Wedding Crashers co-star Vaughn that a sequel is in the works.[25]